Proposal for Pilot Evaporation Pond

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Paradox Valley Unit Proposal for Evaporation Pond water pipelines, access roads, powerlines,telephone and communication cables, a temporary brine disposal pond, and the Paradox Valley Field Station Office. In addition,there are 17 seismic monitoring stations scattered around western Montrose County, Colorado, extreme eastern Utah, and on Forest Service lands. The majority of the facilities are on lands owned by Reclamation. A portion of the project is on public lands managed by the Bureau of Land Management (BLM), and is included in a right-of-way reservation to Reclamation. A network of 15 seismic stations was installed in 1985 to measure seismic activity in the area before commencing brine injection operations. The data showed almost no seismic activity from 1985 to 1990. Both the frequency and magnitude of local seismic events increased after well injection began in 1990. On May 27, 2000, a M4.3 earthquake was induced by injection well operations. In response to this earthquake,the injection rate was reduced from 300 gpm to 230 gpm. Between 1996 and 1999, the well was shut down once annually for routine maintenance. Seismic data showed that the frequency of the seismic events declined substantially immediately following the annual shut down of injecting operations. From this data, it was apparent that periodically suspending operations allows the pressures to dissipate within the injection reservoir, directly correlating to a reduction in earthquake activity. Since learning this, injection has been ceased for a twenty day period twice per year, and brine has continued to be injected at the lower rate of 230 gpm. The two twenty day shut downs annually and reduced injection rate contributed to a reduction of seismicity from 1,142 recorded events in 1999 to 102 recorded events in 2005. At present, 100%brine is pumped into the well at a rate of 230 gpm and injected at required surface injection pressures of over 4,900 psi. The current Maximum Allowable Surface Injection Pressure(MASIP)of the facility is 5,350 psi. The well head was upgraded in the fall of 2009 to increase MASIP from 5,000 to 5,350. The injection well continues to intercept and dispose of up to 115,000 tons of salt per year and remains a cost-effective method to control salinity in the Colorado River(via the Dolores River). The well was projected to effectively store salt for another 10 years provided that acceptable levels of seismicity and well integrity are maintained. However,due to the history of seismic activity,there is a great deal of uncertainty about continuing future benefits of the deep well injection method for salt disposal. Increasingly higher injection pressures may contribute to more frequent and significant seismic activity in the near future. Increases in the magnitude of induced seismicity and/or deteriorating well conditions could cause current usefulness to decline gradually or quickly, depending on the nature of the problem. A portion of the well shaft may have already experienced seismically induced differential displacement, as evidenced by an offset in the well's inner liner that prevented full diameter logging tools from being passed through the restriction. The offset was not significant enough to negatively impact Unit operations. In the event of further deteriorated well conditions or 3