Introduction to Groundwater Geochemistry Reaction Modeling (short course #292)

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Date: December 7, 2020
Location: Las Vegas, Nevada
CEUs: 0.725
Education level: Intermediate



This short course will provide you an introduction to the important geochemical processes that affect groundwater composition and methods for developing reasonable conceptual models using site-specific data.

Geochemical processes that affect the composition of natural groundwater and the movement of groundwater contaminants include a wide variety of interactions between the solution, and solid and gas phases. It is often impossible to predict the impact of these interactions on groundwater composition without a realistic conceptual geochemical model of the system and a means to calculate the interdependent chemical reactions.

This course provides a description of the important geochemical processes, including speciation, oxidation-reduction, precipitation, and adsorption reactions that affect groundwater composition, and provides methods for developing reasonable conceptual models using site-specific data. Conceptual models are combined with an equilibrium modeling code to produce a geochemical model of a site. This course will strengthen your understanding of the fate and transport of inorganic chemicals, and provide you with techniques and software for using site data to develop geochemical models for a given site. In addition to site understanding, geochemical models can be used in a predictive mode for remediation design.

This one-day course provides an introduction to groundwater geochemistry and chemical reaction modeling codes developed for natural and contaminated systems. Emphasis will be placed on inorganic reaction modeling involving major ions and trace metals. The course will include an introduction to the PHREEQC computer code, which is widely used in modeling geochemical processes. Computer sessions integrate examples presented in lecture into realistic problems to provide valuable experience in modeling a specific site. Each session will include a discussion of an important geochemical process and a demonstration of modeling the process with PHREEQC.

Bring your laptop

You should bring a laptop computer to the class to work class examples independently and along with the instructor.

Prior to the class, you should download the PHREEQCI Windows version and its accompanying files from the U.S. Geological Survey website at

During the class, you will receive a comprehensive handout covering the discussion topics and guidelines for setting up, running, and interpreting each class example.

Additional information

Education level

As an intermediate education level course, relevant concepts in aqueous geochemistry will be presented as background material; attendees should possess a basic understand of chemistry and should be knowledgeable in the topics covered in the NGWA courses, “Fundamentals of Groundwater Geochemistry” and “Applications of Groundwater Geochemistry.”

Learning objectives

In this course, you will learn about:

  • Chemical reactions and the groundwater geochemical system
  • Chemical equilibrium calculations
  • Introduction to PHREEQC
  • Ion speciation calculations
  • Gas phase equilibrium
  • Carbonate system
  • Mineral equilibria
  • Mass transfer modeling
  • Oxidation/Reduction modeling
  • Adsorption/desorption processes including surface complexation.

Who should attend?

  • Geochemists
  • Hydrogeologists
  • Engineers
  • Project managers
  • Regulators.

8:00 a.m. The geochemical system, chemical reactions, and modeling

9:30 a.m. Solution phase reactions

10:45 a.m. Break

11:00 a.m. Solution and gas phase interactions

12:00 p.m. Lunch (on your own)

1:00 p.m. Mineral dissolution/precipitation

2:15 p.m. Break

2:30 p.m. Oxidation/reduction potential and redox reactions

3:45 p.m. Break

4:00 p.m. Adsorption/desorption reactions

5:00 p.m. Course adjourns

Fees and registration

On/before November 6

  • NGWA member — $395
  • Nonmember — $545

Starting November 7

  • NGWA member — $495
  • Nonmember — $645

Team discounts up to 10% available. Click for more details.

Full-time students can save 10% by using code STU-20dec292.

Venue and accommodations

Westgate Las Vegas Resort & Casino
3000 Paradise Road
Las Vegas, Nevada 89109
(800) 732-7117
(702) 732-5111

Accommodations: NGWA has secured a limited block of rooms on a first come, first served basis starting at $97 per night, plus resort fees and applicable taxes. This group rate applies to NGWA room block and is valid until the November 6 cutoff date, unless our room block has been filled before that date. Remember, you are responsible for securing your own reservations. Click here to make your reservations online. If you phone to make reservations, be sure to state you are attending this NGWA event and use code SNGW0R. For guest check-in and checkout times, please contact the hotel directly.