TECHNICAL APPENDIX L

GROUND-WATER-QUALITY-MONITORING FRAMEWORK

This appendix outlines issues that relate to the design and implementation of ground-water-quality-monitoring programs. These issues address the unique characteristics of ground water and are consistent with the overall water-quality-monitoring objectives outlined by the Intergovernmental Task Force on Monitoring Water Quality (ITFM).

Developing a General Understanding of the Resource and Monitoring Program Objectives

Ground-water monitoring is a critical component of water-resource-management programs. The hydrologic connections between ground and surface waters mandate that monitoring programs for all water resources be closely linked. By acknowledging this close hydrologic connection, ground-water monitoring can provide critical support to surface- and ground-water-management programs.

Ground-water-quality monitoring is defined as an integrated activity for obtaining and evaluating information on the physical, chemical, and biological characteristics of ground water in relation to human health, aquifer conditions, and designated ground- and surface-water uses. With accurate information, the current state of the Nation's ground-water resources can be better assessed; water-resource protection, preservation, and abatement programs can be run more effectively; and long-term trends in ground-water quality and the success of management programs can be evaluated.

While acknowledging that ground-water monitoring provides critical information to support ground- and surface-water-management programs, it is vital to consider the differences in the spatial and temporal characteristics of ground and surface waters when designing and implementing monitoring programs. Ground water has a three-dimensional distribution within a geologic framework and is characterized by contrasting aquifer and geologic features, limited accessibility (that is, ground water must be sampled through an existing or newly drilled well or a spring), and differences in rates of movement (that is, in general, ground water moves much more slowly than rivers). Therefore, the design and implementation of a ground-water-quality-monitoring program must be based on a thorough understanding of the unique hydrogeological characteristics of the ground-water-flow system under investigation and the locations of particular land uses and other contaminant sources likely to affect ground-water quality. As a result, no one national design and implementation of a ground-water-monitoring program can be recommended. Instead, each State, Tribal, and local jurisdiction must design a monitoring program that takes into account the hydrogeological setting, existing water quality, contaminant source locations, and beneficial uses of the water resource.

An important aspect of any ground-water-quality-monitoring program is the effective sharing and using of data from various sources. One such area of exchange is among programs designed to gather background- or ambient-monitoring data and those designed to gather regulatory compliance-monitoring data. Although the statutory and regulatory requirements for implementing a background- and a compliance-monitoring program may be different, most of the requirements for obtaining data on specific chemical parameters are applicable for both purposes. In cases where appropriate data-quality objectives are met for either background or compliance monitoring, the data will be mutually beneficial for both purposes.

The Ground-Water Focus Group of the ITFM has identified the following general objectives for monitoring programs:

Assess background or ambient-ground-water quality conditions.
Comply with statutory and regulatory mandates.
Determine changes (or lack of change) in ground-water-quality conditions over time to define existing and emerging problems; to guide monitoring and management priorities; and to evaluate effectiveness of land- and water-management practices and programs.
Improve understanding of the natural and human-induced factors (for example, land use activities) affecting ground-water quality.

The Ground-Water Focus Group identified three general types of ground-water monitoring currently (1994) conducted by Federal, State, local, and private organizations to accomplish one or more of the objectives stated above.

Background Monitoring

A wide variety of chemical, physical, and biological contaminants may affect ground-water resources. As a result, background and ambient-ground-water-monitoring programs are designed to establish baseline water-quality characteristics and to investigate long-term trends in resource conditions. The parameters measured in baseline-monitoring programs provide a set of descriptive data on general ground-water conditions.

Monitoring for Specific Land-Use Impacts on Ground-Water Quality

Monitoring programs also typically focus on assessing the impact from contaminant sources that are related to specific land uses. For these regional or localized monitoring efforts, monitoring parameters are identified on the basis of a thorough understanding of the resource to be evaluated and the sources of contamination.

Facility-Based or Compliance Ground-Water Monitoring

Compliance monitoring is conducted in response to specific regulatory requirements or permit conditions [for example, the Resource Conservation and Recovery Act (RCRA), hazardous-waste-unit monitoring or in support of remedial activities [for example, the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) site monitoring].

The next section elaborates on one key component of ground-water-monitoring-program design--the selection of parameters to be monitored to serve as indicators of ground-water quality. The " Ground-Water-Quality-Monitoring Framework" section outlines a detailed framework for designing and implementing a ground-water-monitoring program. This framework is provided as guidance to water-quality-program managers and technical staff to assist in identifying the key components of new or expanded ground-water-monitoring efforts.

Selection of Ground-Water-Quality Indicators

One of the key elements in the design of a water-quality-monitoring program, whether the program is focused on background conditions, land use impacts, or compliance monitoring, is the selection of the properties, elements, and compounds (indicators) to be measured. Ground- and surface-water quality may be characterized by literally thousands of indicators. Selection of indicators for monitoring programs should be based on their relevance to important water-quality issues, such as human health protection, the monitoring objectives outlined above, and the existence of appropriate analytical methodologies. For some water-quality issues, the choice of indicators to be monitored is a simple task; for example, the substances relevant to the issues of nutrient enrichment and salinity are of limited number, and their chemical analysis is inexpensive. In contrast, for the issue of toxic contamination, the selection of indicators is much more difficult because of the large number of potentially toxic trace elements, pesticides, and other synthetic/organic contaminants to consider, and their analysis is expensive.

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. Further, changes in the indicators of interest will occur through time as analytical capabilities improve and become less costly and as knowledge increases about the production of chemicals, geographic usage patterns, and other factors that affect the likelihood of water-quality problems associated with particular constituents.

Criteria for Indicator Selection

Indicators appropriate for ground-water-quality monitoring should meet two general criteria. First, a parameter should be a candidate for monitoring because it fulfills any of or all the following:

Is potentially toxic to human health and the environment, livestock, and beneficial plants; for example, pesticides, volatile-organic contaminants, trace elements, sodium, nitrogen species including nitrite, and nitrate.
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, nitrogen species ammonia, nitrite, and nitrate.
Is an important "support variable" for interpreting the results of physical and chemical measurements; for example, temperature, specific conductance, major ion balance, depth to the water table, and selected isotopes.

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.

Based on these criteria, the following general groups of indicators should be considered for ground-water-monitoring programs.

Field measurements (temperature, specific conductance, pH, dissolved oxygen, alkalinity, depth to water).
Major inorganic ions and dissolved.
Nutrients.
Dissolved organic carbon.
Pesticides.
Volatile organic chemicals.
Metals and trace elements.
Bacteria.
Radionuclides.

Continuing research is needed on techniques for identifying microbiological indicators for ground-water monitoring. Nonetheless, monitoring programs should take into account the many State and local requirements for the assessment of Escherichia coli as a measure of fecal contamination.

Process for Selecting Specific Indicators for Ground-Water-Quality Monitoring

The proposed process for selecting specific indicators for ground-water monitoring is illustrated in Figure 1 and is discussed below.

Figure 1. Process for selecting specific indicators for ground-water-quality monitoring.

Step 1. Analyze Existing Information

The first step in the process is to determine whether there is a recently documented occurrence of the indicator(s) by using existing information. Over the years, a large amount of ambient water-quality data has been collected by many organizations to address a wide range of objectives. Much of these data can be obtained from the U.S. Environmental Protection Agency's (USEPA) STOrage and RETrieval (STORET) and the U.S. Geological Survey's (USGS) National WATer Data STOrage and REtrieval (WATSTORE) system computerized data bases. Many of these data should be useful for selecting indicators, provided that appropriate care is taken to ascertain the manner in which they were collected and analyzed and the individual settings they represent. For example, for pesticides and other trace organic contaminants, it is important that information used to establish the occurrence of these contaminants in the environment be based on appropriately sensitive analytical procedures.

Additional data, some of which may not be in computer files, may be obtained through contacts with other agencies and organizations or through literature reviews. Municipalities, other utilities, and the private sector collect a large amount of water-quality data, often at considerable expense, to comply with statutory and regulatory mandates. For example, under the Safe Drinking Water Act, public water-supply systems routinely collect ambient-water-quality data for use in the operation of their systems or for compliance purposes. These data are not routinely included in national computerized data bases, but may be available from State agencies or individual water utilities and facilities. Similarly, under the RCRA, hazardous waste facilities are required to monitor ground water upgradient and downgradient of waste-disposal units for contaminants likely to be found in the waste stream(s) managed by the facility. If a contaminant is detected, then the facility may be required to monitor for a broader list of constituents ( Federal Register, App. 9, v. 40, pt. 264), whether those constituents are likely to be found at the facility or not. Many of these data should be useful for providing information on locally important indicators and the occurrence of different indicators in relation to different types of facilities and sources.

Step 2. Determine Whether the Contaminant Is Likely to Occur in the Ground-Water System

This step assesses the likelihood that specific indicators, which have no documented occurrence and have not been determined in samples collected from the aquifer system, will be present. This assessment addresses the question: Is it likely that this contaminant is present in this ground-water system? Formulation of a response to this question should take into account what is known about the potential sources of the contaminant(s) of interest, the physical and chemical properties of the contaminants that govern their transport to ground-water systems and knowledge of the local hydrogeology and susceptibility of the aquifer to contamination. Tables 1 and 2 provide examples of indicators that could be considered for monitoring in areas with different types of land use and sources of contaminants. The tables provide a starting point for evaluating the relation between land-use patterns and likely contaminant loading to ground water. For example, ground-water-monitoring programs in regions of agricultural land use should consider pesticides that are or were readily applied to crops in the region, are persistent, and are readily transported to the ground-water system.

Table 1. Indicators likely to be associated with different land uses.

Table 2 provides a suggested set of ground-water-quality-monitoring parameters to be included in facility-based monitoring programs. This list is not intended to substitute for parameters monitored under existing regulatory programs. These parameters, which were identified on the basis of a review of historical facility-based monitoring records, are intended to be used as guidance for new or expanded facility-based monitoring activities. Parameters chosen for a particular facility also should be based on an understanding of the materials handled at the facility, if that information is available.

Table 2. Indicators associated with manufacturing or industrial land use.

Step 3. Test and Validate Contaminant Occurrence

The hypothesis that a contaminant is likely or unlikely to occur in an aquifer system should be tested as part of an " occurrence survey." This step is especially important because of our limited knowledge and understanding of the occurrence of different contaminants in ground water. An occurrence survey would consist of monitoring selected wells in the aquifer system to be sampled. 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. On the basis of the results of this survey, the investigator would determine whether or not the contaminant should be included for subsequent sampling of the system. As knowledge of the occurrence of different contaminants in different environmental settings improves, the uncertainty associated with understanding of indicator occurrence, as well as the need for extensive verification, should decrease.

The above process should be repeated at an appropriate interval (for example, 10 years for background or land-use-impact monitoring) or as deemed necessary, given changes in land and water-management activities, chemical use patterns, or analytical methods. For compliance monitoring, verification of the presence of likely contaminants may be conducted more frequently or as specified under regulation or the conditions of a permit.

This approach to selecting water-quality para-meters is being implemented by several of the States. For example, Florida has focused the set of parameters monitored under their ambient program on the basis of their understanding of local water-quality patterns and contaminant sources. In regions of high agricultural land use, Florida focuses on nitrate and chloride levels in ground water to assess trends in water quality. Similarly, Florida focuses on certain trace metals (for example, arsenic, barium, cadmium, chromium, copper, mercury, nickel, silver, zinc) in regions of industrial land use.

Ground-Water-Quality-Monitoring Framework

The attachment to this appendix outlines a framework of the activities to be included within a ground-water-quality-monitoring program. This framework is intended for program managers and technical staff. The outline highlights the following:

Defining the purpose of the monitoring program.
Coordinating and collaborating with other governmental and nongovernmental organizations.
Designing the monitoring program.
Implementing the monitoring program.
Interpreting data generated by the monitoring program.
Evaluating the effectiveness of the monitoring program.
Communicating the results of the monitoring effort with governmental and nongovernmental organizations, and the public.

For monitoring efforts to be successful, systematic approaches need to be adopted for identifying the chemical, physical, and biological parameters to be measured in ground water. The attachment provides a format for developing and implementing such a systematic approach.

Conclusions

The Ground Water Focus Group concluded that no one national approach to the design and implementation of ground-water-monitoring programs can be recommended. Instead, each State, Tribal, and local jurisdiction must design a monitoring program that takes into account the hydrogeological setting, existing water quality, contaminant-source locations, and beneficial uses of the water resource. By applying the Ground-Water-Quality Indicator selection process described in the section and the Ground-Water-Quality-Monitoring Framework in this Technical Appendix, agencies can develop and implement consistent and defensible approaches for conducting background- and land-use-impact- and compliance-monitoring programs.

The Ground Water Focus Group recognizes that many agencies do not have the capability or sufficient resources to undertake or complete the effort described above in a short timeframe for all aquifers within their jurisdictions. Therefore, it is recommended that agencies work together, to the extent possible, by combining their resources and talents to begin a systematic process of sampling those aquifers that are the highest priority (for example, those that have the largest population and water use) for the full set of indicators identified for each aquifer. Depending on the availability of resources, this approach may extend the amount of time needed to assess all aquifers within an agency's jurisdiction. Nonetheless, the slow traveltimes typically observed in ground water relative to surface water make this tradeoff a reasonable assessment strategy. Contaminants move slowly in ground water, and, as a result, the quality of ground water observed at a well tends to change slowly. Therefore, monitoring ground water in a systematic manner will gradually result in the development of high-quality, comparable data sets that, in the aggregate, will increase knowledge of the occurrence and distribution of indicators in ground water, and environmental settings where different indicators should be included in monitoring programs and, conversely, where it is less necessary to monitor for them.

Ground-Water-Quality-Monitoring

Framework

I. Purpose.

A. Purposes and expectations of participating agencies and customers.

What data are being collected and why?
How will the data be stored and displayed?
How will the results be evaluated?
What does each agency contribute and receive from the monitoring program?

B. Some objectives of the monitoring program.

Need for a general overview (background and ambient monitoring) of ground-water quality in specific aquifers.
Need to identify trends in ground-water quality that are related to regional land-use and nonpoint sources of contamination. Need to identify localized trends in ground-water quality that are related to specific contaminant sources (facility-based/compliance monitoring).

C. Purposes and expectations of monitoring agency.

Near- and long-term requirements and needs that include coordination and collaboration with other agencies and customers, data management, periodic evaluation of monitoring effort, QA/AC considerations, laboratory and field analytical support and service, and training.
Prioritize objectives for monitoring strategies. Prioritization may be based on principle hydrogeologic units, well type, analytes of concern, relation of water quality to land use, surficial aquifers/artesian aquifers, and timeframe for monitoring activity.

D. Environmental Indicators--Selection of environmental indicators to measure achievement of monitoring agency objectives and purposes.

Select indicators on the basis of the type of monitoring activity--ambient (baseline), evaluation or detection, and compliance (response and remediation).
Select indicators on the basis of other objectives of the monitoring program from coordinators and collaborators.

II. Coordinate/collaborate.

A. Identify potential participants.

Establish a working relation with Federal, State, tribal, local, academic, and private agencies.
Communicate project objectives and goals.

B. Define roles of participants.

Participants may provide financial or technical information, interpretation of data, and or resource, technical, or regulatory management expertise.

C. Define needs of users and establish data- quality objectives.

If possible, incorporate needs of other agencies/groups who use the information into the purposes of the program.
Ensure the inclusion of data qualifiers with stored data so others know the accuracy and precision of the environmental data that are being collected and analyzed.

III. Design

A. Define objectives and scope of project.

Hydrogeologic units to be monitored.
Analytes of concern.
Well types.
Land use.
Timeframe.
Financial considerations.
Personnel considerations.
Analytical considerations.
Data-management considerations.
Other resources and constraints.

B. Existing environmental setting--Identify and describe the existing environmental setting, which includes its hydrology (surface and ground waters), biota, and resource use.

Geohydrology.
Biota.
Resource use.

C. Existing water-quality problem--Evaluate available information to provide a current conceptual understanding of existing ground-water-quality problems; depict the known or suspected ground-water-quality conditions, problems, or information gaps; and identify management concerns and alternatives.

Provide a current conceptual understanding of factors that affect spatial and vertical distribution in water quality.
Evaluate past and present water quality on the basis of existing information. Evaluate existing information in terms of quality, representativeness, and usefulness; for example well construction impacts on water quality or heterogeneities in the natural system.
Identify management concerns and alternatives. Identify and prioritize problems, needs, and information gaps.

D. Environmental indicators and data parameters--Determine the appropriate or applicable environmental indicators and related chemical, physical, biological, and ancillary data parameters to be monitored. Indicator selection is related to the following criteria:

Program objectives (ambient, detection/evaluation, and response/compliance).
Existing hydrogeology.
Natural setting (physiography, climate, land cover).
Condition/character of the sampling site (well, spring, lysimeter).
Past/present land-use activities.
Designated uses of ground water (drinking water, recharge to surface water to support recreation).

E. Reference conditions--Establish reference conditions for environmental indicators that can be monitored to provide a baseline ground-water-quality assessment.

F. Confidence level--Define the level of confidence needed for the data to support testing management alternatives.

G. Data-set characteristics.

Determine basis for monitoring design that will allow successful interpretation of the data at a resolution (scale) that meets project purposes.
The basis for monitoring should include statistical reliability and geographic, geohydrologic, geochemical, biological, land use/cover, and temporal variability.

H. Quality assurance plan--Develop a quality-assurance plan that documents data accuracy and precision, representativeness of the data, completeness of the data set, and comparability of data relative to data collected by others.

I. Monitoring design--Design a sampling plan for existing or proposed sites. Design may include sampling-site distribution and location (wells and springs) and environmental indicators (physical, chemical, biological, ancillary).

Design the general-ground-water monitoring network on the basis of the conceptual study design and the study and characterization of the area.
Select and characterize the specific sites. Document the basis for the selection of each existing or proposed site as it fits the conceptualization, network design, and data quality objectives.
Design the collection points at the site(s).
Identify personnel and equipment needs.
Estimate costs of network.
Ground-water indicators selected may be constituent based, administrative, or part of a tiered or screening monitoring approach. For further information, refer to the ITFM discussion and matrices for ground-water indicators.

J. Data collection methods--Develop sampling plans and identify applicable protocols and methods, and document data to enable data comparison with other monitoring programs in accordance with QA/QC requirements. Refer to program-specific guidelines. Identify personnel and equipment needs.

Develop a plan for sample collection.
Develop data documentation plan/chain of custody/labeling.
Identify personnel, equipment, and training needs.
Develop health and safety documents.
Estimate cost of data collection.

K. Timing--Describe duration of sampling program and frequency and seasonality of sampling.

L. Field and laboratory analytical support--Identify applicable field and laboratory protocols or performance-based criteria, which include detection level, accuracy, precision, turnaround time, and sample preservation.

Identify personnel, equipment, and other support needs for field and laboratory.
Identify field and laboratory QA/QC requirements.
Select performance-based criteria for evaluation of analytical capabilities and results.
Estimate cost of field and laboratory analytical support.

M. Data management--Describe data-management protocols, which include archiving, sharing, and security. Ensure the inclusion of metadata, such as location (latitude and longitude), date, time, a description of collection and analytical methods, and quality-assurance data.

Define user requirements.
Considerations for the conceptual design of the digital system.
Test plan and standards--Basis for hardware and software selection or development of a digital system.
Functional analysis of a digital system.
Physical design of a digital system--System selection and (or) development.

N. Training.

Activities related to monitoring that require training, these include designing, collecting, managing, interpreting, and reporting and communicating water-quality data.
Support activities that require training, these include data-management activities and laboratory analysis.

O. Interpretation--Identify statistical/analytical methods that are relevant to the data within specified confidence levels for program purposes.

Understand the sample size.
Understand the parameters.
Identify statistical/analytical methods (refer to Section V.).

P. Communications.

Identify technical and lay audiences.
Identify mechanisms and formats for presenting/distributing information; for example press releases, public meetings, agency meetings, conferences, popular publications, agency reports, and journal articles.

Q. Costs.

Determine the program costs and sources of funding.
Include in the cost estimates implementation, interpretation, and communication activities of the monitoring program.

R. Program modification--Develop feedback mechanisms to fine-tune/improve design.

IV. Implementation.

A. Establish and document sites (selected during design and planning stages).

Construct wells, shelters, gage houses, staff gages, and other structures as needed in preparation for data collection.
Document ancillary data for sites.

B. Collect data.

Collect data according to specified monitoring design and protocols.
Coordinate with other agencies as appropriate.

C. Review results.

Review data-collection activities to ensure that protocols and the QA plan are being followed.
Review data-collection activities to ensure that data are complete and meet stated purposes.

D. Store and manage data.

Archive data so that the accuracy and precision are maintained.
Review data in accordance with data management plan.

E. Share data---Provide lists of data for other agencies upon requests.

F. Prepare data summaries.

Provide information to managers periodically.
Provide information to collaborators and cooperators according to schedules.

V. Interpretation.

A. Data reliability--Define the accuracy and precision of the hydrogeologic and ancillary environmental data.

B. Interpret data to meet stated program purposes--Interpret the data, which include a description of the ground-water-resources system, by using existing environmental and ancillary data to provide information necessary to making management decisions related to water quality.

Geohydrologic systems analysis.
Hydrogeochemical analysis.
Comparison of data to monitoring objectives.

C. Statistical methods and model documentation--Use statistical packages and deterministic models that are well documented.

D. Assess management impacts--Evaluate management alternatives and assess their impacts on the resource.

E. Coordinate interpretations--Coordinate the interpretations of data with collaborators and the user community.

VI. Evaluate monitoring program.

A. Meet goals and objectives--Determine if monitoring program goals and objectives are being met.

Assess usefulness of project data/information for local, regional, and national assessments.
Evaluate the need for program modifications and develop appropriate recommendations for ground-water monitoring.
Evaluate organizational concerns and coordination for private sector interface and local, State, and Federal interface.

B. Identify problems--Identify any monitoring problems associated with collecting and analyzing samples; storing, disseminating, and interpreting data; and reporting the information to managers and the public.

Evaluate the strengths and weaknesses of the monitoring-program design.
Evaluate the data-collection and the interpretation methods.
Evaluate the information-transfer methodologies used to report the data and information to resource managers, the public, and the scientific community.

C. Evaluate costs--Evaluate the costs of the monitoring program.

D. Feedback--Use results of evaluating monitoring program to identify current and future needs.

VII. Communication.

A. Coordinate--Participate in the distribution of information to and with other agencies and interested groups, such as environmental, industrial, and agricultural constituents.

B. Prepare and distribute technical reports--Describe current water-quality conditions; spatial distribution; temporal variability; and sources, causes, transport, fate, and effects of contaminants based on monitoring results to humans, aquifers, and ecosystems as appropriate.

C. Communicate with multiple audiences--Prepare lay reports or executive summaries for nontechnical audiences and peer review reports for technical audiences.

D. Presentations--Make presentations to assist management and the public in understanding the significance of results. Presentations could involve the use of public information networks, which include newspapers, radio, and television.

E. Provide available data--Provide available data for other data users as needed.

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Last modified: Fri Nov 8 16:33:37 1996