Case Study: Water Expansion Project Resolves Pollution Issues, Leads To Scientific Breakthrough

By Sarah L. Raker, PG, CHG Senior Principal Geologist, MACTEC Engineering and Consulting, Inc.

A plume of toxic groundwater discovered in a small neighborhood in Chico, CA (pop. 88,000; about 90 miles north of Sacramento) more than six years ago has not only been successfully addressed, but has also resulted in a significant breakthrough in better understanding the region's geological history – core samples taken from drilling groundwater monitoring wells in the Skyway Homes Subdivision area are providing important information for scientists.

Zurich, Switzerland-based ABB (www.abb.com) provides power and automation technologies for utility and industry customers. The ABB Group of companies currently operates in more than100 countries and employs about 120,000 people. ABB purchased Combustion Engineering; that firm's subsidiary once manufactured aluminum windows and shower stalls. Operations ceased in 1977, 13 years before ABB purchased Combustion Engineering in 1990. A solvent, trichloroethylene (TCE), was detected in water supply wells located at the former manufacturing facility and in nearby domestic and irrigation wells.

Although ABB had no role in polluting the groundwater, the California Department of Toxic Substances Control (DTSC) determined that they were still legally bound to clean up the site. ABB reimbursed the state for nearly $1M already spent on cleanup and another $2M to put in water lines that supplied residents with clean water provided by the California Water Service Company.

MACTEC was retained by ABB to assist with the cleanup, providing environmental consulting and construction oversight for investigating and remediating elevated levels of TCE in the groundwater.