The use of isotopic methods in groundwater investigations is gaining widespread acceptance among hydrogeology professionals. Well-established techniques such as using stable isotopes of hydrogen and oxygen as markers of water source have been applied in water resource investigations for several decades. Isotope methods are powerful tools when applied to the intractable problems of source attribution for the most common groundwater contaminants, including nitrate, VOCs, and perchlorate. Radioactive isotopes can be used to determine groundwater age, or the time since water entered the saturated zone, which has important implications for delineating groundwater or contaminant flow pathways, identifying recharge areas, and providing a measure of aquifer vulnerability. GRA seeks to provide a forum for disseminating proven methods, practical applications, and problem-solving techniques involving isotopes and groundwater investigations.

Join us March 28 and 29, 2007 at the Hilton Hotel in Concord, California for the 3rd Event in GRA's Tools and Technologies Series.

March 28 - Isotope Methods for Groundwater Investigations Course

Instructors: Dr. Carol Kendall (U.S. Geological Survey) and Dr. Jean Moran (Lawrence Livermore National Laboratory)

Course Description:

The objective of this course is to provide an overview of practical applications of environmental isotopes for managing groundwater resources, determining aquifer vulnerability to contamination, and tracing sources of water, nitrate, and other contaminants in groundwater and surface water systems. The class will start with a brief introduction to the fundamentals of isotope geochemistry. Topics include relevant educational resources, isotope terminology, fractionation mechanisms, sample collection and analysis methods, and quality assurance of contract laboratories.

The main focus of the first section of the course will be practical applications of stable isotopes for tracing waters, solutes, water-rock interaction, and biogeochemical reactions in hydrologic systems. Emphasis will be on how to make effective use of water and nitrate isotopes to determine sources of water and nitrate in groundwater and surface waters. Other topics include applications of carbon and sulfur isotopes for tracing biogeochemical reactions and contaminant sources, and methods for tracing organic contaminants in groundwater. A major component of this section is the presentation of a diverse set of short case studies which demonstrate the power of isotope techniques for resolving water quality problems.

Understanding groundwater age, or the time since groundwater entered the saturated zone, can have important implications for managing groundwater resources and determining aquifer vulnerability to contamination. Knowledge of the groundwater age distribution in a basin can be used to delineate groundwater or contaminant flow pathways, identify recharge areas, and provide a measure of hydraulic conductivity. In this section of the course, participants will be exposed to the various methods for determining groundwater residence time, and guided through all stages of the tritium-helium technique of groundwater age dating, from sampling and analysis to data reduction. Participants will see the sampling method for dissolved gases in groundwater, learn about mass spectrometric methods for measuring helium isotopes and other dissolved gases, calculate groundwater ages using real data from groundwater samples in California, and learn how to apply groundwater ages to water resource investigations. Emphasis will be on understanding the meaning of a groundwater age from a well water sample, including limitations in its interpretation, and on proven applications.

Instructor Bios:

Dr. Carol Kendall is a 4th generation Californian who got her BS and MS at UC-Riverside, and later her PhD at the University of Maryland while working at the USGS headquarters in Virginia. Since 1990 she has been the head of the Isotope Tracers research project at the USGS regional office in Menlo Park. The purpose of this project is to develop new isotope methods and applications to solve problems of national importance. Her main research focus is tracing sources of nutrients, organics, and water in human-impacted aquatic ecosystems. She is the co-editor of the 1998 book “Isotope Tracers in Catchment Hydrology” and has taught dozens of isotope hydrology short-courses over the past 20 years for the USGS and various federal, state, academic, and international organizations.

Dr. Jean Moran is a researcher in the Isotopic Tracers and Transport group at Lawrence Livermore National Laboratory. Her research focuses on using natural isotopes and introduced isotopic tracers to examine geochemical and transport processes in the vadose zone and in groundwater. She is currently principal investigator and LLNL project director for the Groundwater Ambient Monitoring and Assessment project sponsored by the California State Water Resources Control Board. Dr. Moran has a Ph.D. in Geochemistry from the University of Rochester, Bachelor’s degrees in physics and geology from the University of Rochester and a Master’s degree in geophysics from the University of Washington. She has been an author on more than 30 journal publications.

March 29 - Applications of Isotope Tools to Groundwater Studies Symposium

Symposium sessions will cover a variety of topics, including but not limited to:

Surface Water – Groundwater Interaction

• Tracing artificial recharge at surface spreading sites
• Use of isotopes to monitor aquifer storage and recovery (ASR)
• Tracking stream recharge along losing stream reaches
• Induced recharge via pumping
• Isotope tracers in areas of groundwater banking
• Use of isotopes to examine biogeochemical processes in the hyporheic zone
• Examining vadose zone transport using isotope methods

Contaminant Transport and Geochemical Evolution of Groundwater

• Multi-tracer or multi-isotope studies
• Nitrate source attribution using isotope tracers
• Characterization of nitrogen fate, transport and cycling in the saturated and vadose zones
• Perchlorate source attribution using isotopes of Cl and O
• Use of sulfur, carbon, boron or halogen isotopes in fate and transport studies
• ‘Heavy’ stable isotopes (e.g., Cr, Pb), or radiogenic isotopes (Sr, U, etc.) in environmental forensics applications
• Isotope methods for examining multi-component mixtures

Aquifer Vulnerability and Water Residence Time

• Age dating groundwater using radioactive isotopes (e.g., tritium (3H), 3H-Helium, 14Carbon); application of other groundwater age tools (CFCs, SF6, 4Helium)
• Using groundwater age to validate or calibrate flow and transport models
• Identifying paleowater using long-lived isotopes and other age/climate proxies
• Applications of ‘young’ groundwater tracers in active recharge areas
• Tracer techniques for examining groundwater mixing/dispersion
• Communication of results from isotope studies to clients, sponsors, purveyors, and the public

Experts from academia, consulting, regulatory agencies and industry will participate in moderated speaker sessions and posters sessions. The combination of invited speakers and experts from key areas, along with talks chosen from submitted abstracts, will make this an important event for all professionals considering application of isotopic techniques in groundwater investigations.

Exhibitors: ARS Technologies, Inc. | Laboratory Data Consultants (LDC) | Los Gatos Research | Instrumentation Northwest | Precision Sampling, Inc. | ZymaX Forensics

Exhibitors and Sponsors
If you are interested in exhibiting your organization's services or products, or being an event sponsor, please contact Mary Megarry at mmegarry@nossaman.com or 916-446-3626. GRA welcomes co-sponsors, lunch, refreshment and reception sponsors.

Associated Event (after Isotope Course):
GRA San Francisco Bay Branch Meeting – ISOTOPES: Old Dogs - New Tricks
March 28, 2007 - Concord, CA