

In the wake of news that a second earthquake in the last month has shaken an area of north-east Greeley around a deep “injection well” used to bury waste fluid from the drilling process known as fracking, Colorado regulators have made an agreement with the company that owns the well to suspend operations there.

“The Colorado Oil and Gas Conservation Commission this week directed High Sierra Water Services to stop disposing wastewater into one of its Weld County injection wells,” regulators reported in a release Tuesday.

On Monday at 11:27 a.m. Mountain Time, a 2.6 magnitude earthquake rumbled 2.5 miles under the earth about 5 miles north-east of Greeley, the city at the heart of the northern Front Range gas patch. The quake came from roughly the same spot that generated a 3.4 magnitude quake on May 31st and that fueled speculation that the High Sierra injection well was the cause.

Geologists have long noted that injection wells generate temblors.

In its release, the commission reported that, apart from the earthquakes, University of Colorado seismologists had “picked up additional evidence of low-level seismic activity near the injection site.”

Read the full release below:

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RELEASE

COGCC halts activity at injection well; seeks additional review

The Colorado Oil and Gas Conservation Commission this week directed High Sierra Water Services to stop disposing wastewater into one of its Weld County injection wells.

The company agreed to a 20-day halt to wastewater injection as a cautionary step the COGCC believes necessary to gather and further analyze more information to determine whether injection at the site is tied to recent seismic activity recorded within the general vicinity of the well.

Ongoing monitoring by a team of University of Colorado seismologists has picked up additional evidence of low-level seismic activity near the injection site, including a 2.6-magnitude event Monday afternoon. The additional data comes after a 3.4 magnitude earthquake shook the Greeley area May 31.

“In light of the findings of CU’s team, we think it’s important we review additional data, bring in additional expertise and closely review the history of injection at this site in order to more fully understand any potential link to seismicity and use of this disposal well,” said COGCC director Matt Lepore.

The COGCC will undertake several actions over the shutdown period to include: evaluation of baseline, historical seismic activity; continued coordination with the CU team; coordination with the U.S. Geological Survey and Colorado Geological Survey; evaluation of other disposal wells in the area; and a detailed review of data associated with the well in question, including further examination of injection rates, pressures and volumes.

The company immediately agreed to COGCC’s request, and shut the well down on Monday.

The well, labeled by the company as C4A, is located east of the Greeley-Weld County Airport. It was permitted by COGCC in March 2013 and injection began in April of 2013.

The COGCC has delegated authority by the U.S. Environmental Protection Agency, to regulate Underground Injection Control wells for oil and gas wastewater (known as Class II UIC wells).

Such wells must be analyzed for a variety of geologic factors before permits are issued; disposal of the wastewater must also occur at the proper rate and pressure to ensure it is safely deposited in the formation.

A history and overview of underground injection wells and seismicity in Colorado is available at the COGCC’s website under the LIBRARY tab on the left hand side of the page. Scroll down to “Underground Injection Control and Seismicity.”