San Francisco Bay Branch Meeting - Geology and Geochemistry of Chromium Sources in California's Groundwater




The San Francisco Bay Branch is pleased to present:

 "Geology and Geochemistry of Chromium Sources in California's Groundwater"


William E. Motzer, PhD, PG, CHG,

Senior Geochemist, TODD Groundwater

Wednesday, March 15th



Chromium (Cr) including Cr(VI) species occur in California’s groundwater from both anthropogenic and geogenic (natural sources). Past investigations largely focused on anthropogenic sources (e.g., added to water as a biocide) popularized by the 2000 movie Erin Brokovitch. More recently, groundwater investigations have considered geogenic sources with California having a unique geologic framework, including numerous areas of ultrabasic and serpentinized ultrabasic rocks. These contain abundant Cr and Cr minerals, which when weathered, can undergo transformation in the critical zone to Cr(VI) complex oxyanions.

Groundwater in alluvial aquifers derived from ultrabasic and serpentinized terrain can contain Cr(VI) oxyanions, particularly chromate (CrO42–) and dichromate (Cr2O72–), generally forming under alkaline pH and oxidizing (+Eh) conditions. In other areas, Cr(VI) oxyanions can sorb to hydrous ferrous oxide (HFO) coatings on quartz grains. For projects in which recycled water (RW) is introduced to replenish depleted groundwater supplies, changes in pH and Eh have the potential for liberating Cr(VI), arsenic, and lead. Leaching tests with stabilized RW and geochemical modeling, using USGS PHREEQC and PHAST models can be used to assess possible impacts to groundwater by these constituents.


Speaker Bio:  

William E. (Bill) Motzer is a registered California Professional Geologist (PG) and Certified Hydrogeologist (CHG), with PG registrations in five other states.  Bill has extensive experience in conducting surface and subsurface water quality chemistry and environmental forensic investigations. Bill is a recognized expert in water quality and forensic geochemistry, with particular expertise in stable and other isotopic “fingerprinting” and age dating techniques, water quality/contaminants, and emerging contaminant geochemistry. He has conducted numerous environmental projects, throughout California and other western states. He is a past President of the San Francisco Bay Branch of the Groundwater Resources Association of California (GRA), past Vice President for the International Society of Geochemistry and Health, and contributing editor to the California Section of the American Chemical Society’s (ACS) newsletter – the Vortex (



5:30 - 6:30 p.m. - No-Host Social and Registration
6:30 - 7:30 p.m. - Dinner and Announcements
7:45 - 8:30 p.m. - Speakers
8:30 - 8:45 p.m. - Questions and Answers


Fish – Baked fresh Atlantic salmon with herb butter, served with rice pilaf and fresh seasonal vegetables
Meat – Rosemary chicken, garlic mash potatoes and fresh vegetables
Vegetarian – Portobello mushroom ravioli with an Alfredo pesto sauce



$45 for Members
$50 for Non-Members
$10 for Student attendees




TestAmerica is the leading environmental testing firm in the United States, with over 80 locations and 2,000 professionals providing innovative technical expertise and comprehensive analytical testing services. As the recognized technical industry leader, we provide online access to our top industry professionals through our “Ask the Expert” program allowing any individual with a question related to environmental testing to access the thoughts and opinions of recognized experts in their field through a free, easy to use online platform. TestAmerica is dedicated to exceptional service and solutions for our clients’ environmental testing needs.

For additional information contact:

Sr. Account Executive
1220 Quarry Lane
Pleasanton, CA 94566
Cell 602.501.9322



GRA San Francisco Bay Branch is interested in supporting university science students. Our Scholastic Sponsorship Program is an opportunity to publicize your business while contributing toward a good cause. Your sponsorship will be acknowledged in the announcement, at the meeting, and space will be provided for a small display and brochures. Please contact Abigail Madrone at or at 530-756-5905 for details.

 If you have any announcements or questions, please contact the Branch President, Eric Sandberg ( at 415-786-7244, or Branch Treasurer David W. Abbott ( at 510-928-4543.

We are actively looking for potential speakers. If you have a topic or suggestion, please contact the Branch President, Eric Sandberg ( at 415-786-7244


Wed, March 15, 2017
5:30 p.m. - 8:45 p.m.

Event has ended


Hs Lordships
199 Seawall Drive
Berkeley, California 94710