The Casa Diablo geothermal power plants have been in operation since the mid-1980s, and expansion of the geothermal power plants into the Basalt Canyon area began in 2006. These power plants are on National Forest System lands managed by the Inyo National Forest near Mammoth Lakes in Mono County, California. An expansion of the monitoring program is necessary for additional power to be produced from the Basalt Canyon area.
The Casa Diablo IV (CD IV) Geothermal Development project in the Long Valley Known Geothermal Resource Area (KGRA) was approved by the U.S. Bureau of Land Management (BLM) and United States Forest Service in their respective records of decision on August 12, 2013. The BLM required a groundwater monitoring plan to be in place before power plant operation. As part of this required groundwater plan, the project discussed in this report planned and drilled two new monitoring wells within the geothermal well field in the Basalt Canyon area. After drilling and collecting baseline data for these monitoring wells, two existing, idle geothermal wells were flow tested for 28 days to monitor connectivity between the warm water aquifer and the hot geothermal reservoir. This project was executed in coordination with the Long Valley Hydrologic Advisory Committee.
This project sought to expand the existing monitoring program to gather additional evidence concerning any hydrologic connection between the groundwater well production zone and the deeper geothermal reservoir beneath the western part of Long Valley KGRA. Assessment of the new monitoring wells and the data collected during the 28-day test concluded that no hydraulic connection with the geothermal reservoir exist, and the new monitoring wells would adequately serve as shallow monitoring points during development of the fourth phase of the expansion project.
Author(s)
Janice Lopeman; Lara Owens, P.G.; Paul Spielman; Mark Hanneman; John Akerley
