The intent of the proposed Project is to develop a monitoring well to collect water quality samples to monitor potential effects of nearby geothermal energy production. The Casa Diablo IV Geothermal Development Project, which is located to the north and east of the shallow groundwater aquifer on which the Mammoth Community Water District (District) relies for its main water supply, has raised concerns about the potential impacts of this additional geothermal energy production on the District’s groundwater supply. This monitoring well will permit the District to collect water quality data to monitor the effects of the additional geothermal energy production activities in order to evaluate the need for action should impacts occur.
The Project includes the drilling of a 5-inch monitoring well. The proposed Project site will be accessed from Center Street utilizing an existing graded driveway at 161 Center Street. Approximately, 0.4 acres will be utilized by the drilling equipment. A temporary drilling pad will be constructed on approximately 0.2 acres of The Parcel and best management practices will be installed and maintained to mitigate dust and water quality impacts. Trees will be removed only as needed to safely gain access for the well drilling equipment. All portions of the site not previously disturbed, or needed for access, will be revegetated with stockpiled topsoil from the site following completion of the well. Waste generated during drilling will be trucked off site.
The Project site is located in a mixed-use area. Residential units are located to the north and west and a commercial building is located to the east. A housing project is currently planned on portions of the proposed Project site. No impacts to the existing or proposed housing projects or commercial entities will result from this project. Other than the temporary drilling activities and well installation activities, which are expected to take approximately two months, there will not be any additional disturbance.
After the proposed monitoring well has been completed, data samples will be collected on a quarterly basis. These samples will be utilized consistent with the CD-IV Geothermal Development Project Groundwater Monitoring and Response Plan.