Monitoring ground-surface heating during expansion of the Casa Diablo production well field at Mammoth Lakes, California

By: , and 



The Long Valley hydrothermal system supports geothermal power production from 3 binary plants (Casa Diablo) near the town of Mammoth Lakes, California. Development and growth of thermal ground at sites west of Casa Diablo have created concerns over planned expansion of a new well field and the associated increases in geothermal fluid production. To ensure that all areas of ground heating are identified prior to new geothermal development, we obtained high-resolution aerial thermal infrared imagery across the region. The imagery covers the existing and proposed well fields and part of the town of Mammoth Lakes. Imagery results from a predawn flight on Oct. 9, 2014 readily identified the Shady Rest thermal area (SRST), one of two large areas of ground heating west of Casa Diablo, as well as other known thermal areas smaller in size. Maximum surface temperatures at 3 thermal areas were 26–28 °C. Numerous small areas with ground temperatures >16 °C were also identified and slated for field investigations in summer 2015. Some thermal anomalies in the town of Mammoth Lakes clearly reflect human activity.Previously established projects to monitor impacts from geothermal power production include yearly surveys of soil temperatures and diffuse CO2 emissions at SRST, and less regular surveys to collect samples from fumaroles and gas vents across the region. Soil temperatures at 20 cm depth at SRST are well correlated with diffuse CO2 flux, and both parameters show little variation during the 2011–14 field surveys. Maximum temperatures were between 55–67 °C and associated CO2 discharge was around 12–18 tonnes per day. The carbon isotope composition of CO2 is fairly uniform across the area ranging between –3.7 to –4.4 ‰. The gas composition of the Shady Rest fumarole however has varied with time, and H2S concentrations in the gas have been increasing since 2009.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Monitoring ground-surface heating during expansion of the Casa Diablo production well field at Mammoth Lakes, California
Volume 39
Year Published 2015
Language English
Publisher Geothermal Resources Council
Contributing office(s) Volcano Science Center
Description 7 p.
Larger Work Type Conference Paper
Larger Work Title Geothermal Resources Council Transactions
First page 1007
Last page 1013
Conference Title GRC Annual Meeting & GEA Geothermal Energy Expo
Conference Location Reno, NV
Conference Date Sep 20-23rd, 2015
Country United States
State California
Other Geospatial Casa Diablo Production Well Field, Mammoth Lakes, California
Online Only (Y/N) N
Additional Online Files (Y/N) N