HINKLEY >> The U.S. Geological Survey is bringing a mobile lab here to test residents' wells and quickly provide test results, officials say. The testing, which will happen later this month, for about 60 residents, is to advance a $5.4 million USGS study of Hinkley's groundwater to determine how much of Hinkley's plume of chromium-6 is occurring naturally and how much was put there by Pacific Gas & Electric Co., said John Izbicki, the USGS geologist, who is heading up the research project.