Steps Toward a “Best Practices” Protocol - Induced Seismicity Potential in Energy Technologies - page 134

BOX 6.1
The Department of Energy Protocol for Addressing Induced Seismicity
Associated with Enhanced Geothermal Systems
The elevated downhole fluid pressures used in EGS induce fracturing that can result in a level of induced
seismicity that is felt at the surface and that in some cases has caused serious concern among those living
nearby (see Chapter 3). To attempt to avoid the repeated occurrence of such results, while encouraging the
future use of geothermal resources, a protocol has evolved to serve as a guide for EGS developers within
the United States as well as internationally. The most current protocol, developed by the Department of Energy
(Majer et al., 2012), “outlines the suggested steps that a developer should follow to address induced seismicity
issues, implement an outreach campaign and cooperate with regulatory authorities and local groups.” This
sequence of seven steps can be summarized as follows:
STEP 1. Perform Preliminary Screening Evaluation. Assess the feasibility of the proposed
project as to its technical, socioeconomic, and financial risks in order to provide an initial measure of the
project's potential acceptability and ultimate success. Review local regulatory conditions, the level of natural
seismicity, and the probable impacts of the project on any nearby communities and sensitive facilities.
STEP 2 . Implement an Outreach and Communication Program. Before operations begin,
implement a public relations plan that describes the proposed operations, determine the resulting concerns,
address those concerns, and then periodically meet with the locals to explain the upcoming operations and
the results of the work done to date.
STEP 3. Review and Select Criteria for Ground Vibration and Noise. Identify and evalu-
ate local environmental and regulatory standards for induced vibration and noise. Develop appropriate
acceptance criteria for an EGS project.
STEP 4. Establish Local Seismic Monitoring. Collect baseline data on the regional seismicity
that exists before operations begin. Install and operate a local seismometer array to monitor the project's
operations.
STEP 5. Quantify the Hazard from Natural and Induced Seismic Events. Estimate the
ground shaking hazard from the natural seismicity to provide a baseline to evaluate the additional hazard
from the induced seismicity.
STEP 6. Characterize the Risk of Induced Seismic Events. Characterize the expected induced
ground motion and identify the assets and their vulnerability within the area likely to be influenced by the
project.
STEP 7. Develop a Risk-Based Mitigation Plan. If the level of seismic impacts becomes
unacceptable, direct mitigation measures are needed to further control the seismicity. A “traffic light” system
can allow operations to continue as is (GREEN), or require changes in the operations to reduce the seismic
impact (AMBER), or require a suspension of operations (RED) to allow time for further analysis. Indirect
mitigation may include community support and compensation.