A proposed 166-well oil and gas project in suburban Denver could imperil a decades-long, multimillion-dollar effort to prevent carcinogenic chemicals stored on one of the nation’s most contaminated industrial sites from leaking into groundwater, letters from federal and state officials show.

Regulators expressed concern in May that drilling underneath and near the Lowry Landfill Superfund site could cause small cracks in bedrock cradling millions of gallons of toxic waste in 78 unlined trenches. These fissures could allow contaminants to enter an aquifer system that millions of Coloradans rely on, the U.S. Environmental Protection Agency wrote to Civitas, the operator requesting permission to drill. The EPA oversees a complex 40-year effort to protect the health of millions of people living around the site.

The agency’s concerns stem from the issues that have long surrounded  hydraulic fracturing, or fracking, a drilling process that has led Colorado in the last decade to become the nation’s fourth largest oil-producing state. The method involves pumping sand and millions of gallons of water and chemicals roughly a mile under the surface to crack shale, and release oil and gas. Civitas is one of the top five producers in Colorado.

“The EPA is concerned that hydraulic fracturing surrounding and underneath the site could lead to a significant unintended release of hazardous substances,” the agency wrote in May to Dan Harrington, who leads Civitas’ development initiatives. This “contamination is held in place by a bedrock layer which could, under certain conditions, be subject to microfractures from fracking.”

In response, Civitas sent a letter to the EPA in September and committed not to drill under the site, saying: “This precaution is not due to any risk associated with oil and natural gas development, but a desire to protect the Superfund remedy that is in place and operating effectively.”

Civitas refiled its drilling plan on Feb. 23 after making a series of revisions requested by state regulators.  A 60-day public comment period ends April 23, and a hearing on the proposal is scheduled in front of the Energy and Carbon Management Commission for June 26. [WD residents may make comments. This area is not the Lowry Vista site. All of the described area is outside of Denver]

What about water in Aurora Reservoir?

The operator’s agreement not to drill under the Superfund site failed to reduce the anxiety of scores of households near the 50-square-mile proposed oil and gas project, which includes wells near the Aurora Reservoir. The facility is part of a system of reservoirs that store drinking water for about 390,000 people and is a popular recreation area.

Drilling currently exists about five miles from the Superfund site. Civitas is proposing well pads much closer — within about two miles. But horizontal pipes that extend beneath the proposed production area could come even closer to the site boundary.

The potential for Civitas’ Lowry Ranch oil and gas plan to disturb sensitive Superfund containment efforts brought to the fore long-running uncertainty among technical experts about whether nearby industrial operations, such as fracking, could trigger seismic activity. The U.S. Geological Survey and state agencies mapped faults near the site, as well as near the Aurora Reservoir’s dam.

Questions remain about the presence, and possible growth, of a fault at the northern end of the Superfund site and whether it’s in part responsible for allowing chemicals to leak and create a 3 mile-long underground plume. The EPA says this plume doesn’t present a risk to groundwater or surface water.

Scientists have attributed earthquakes in Colorado, Oklahoma and Texas, to a surge in oil and gas operations over the last decade. These temblors were caused by injection wells, which companies drill deep into the earth and use to dispose of millions of gallons of wastewater that flows back up from fracking operations, studies found.

Hydraulic fracturing features a brief application of pressure to rock formations to release oil and gas, while wastewater injection is “an ongoing process that injects significant volumes of wastewater over long periods of time,” said Jill Carlson, an engineering geologist at the Colorado Geological Survey.

“While weak seismic events associated with fracking can be detected by seismometers, I am not aware of any surface shaking, movement or surface/near surface damage caused by fracking,” added Carlson, who is the survey’s deputy director and land-use program manager.

Worry about the effects on public health

The Lowry Ranch oil and gas project is proposed on land owned by the Colorado State Land Board on the fringes of Aurora, the state’s third largest city.

Much is at stake: Energy companies are planning large projects ever closer to Denver suburbs, where the industrial activity exposes hundreds of thousands of residents to air pollution, spills, truck traffic and other hazards.

Proposed drilling near a Superfund site also raises new health and safety concerns residents say aren’t adequately addressed in state or local regulations. Increasingly, residents are demanding stricter rules about where fracking can take place and detailed studies that provide benchmarks for how much activity should be allowed.

“The county must insist on studies to understand the potential risks associated with fracking-induced seismicity on both the Lowry Landfill Superfund Site — and the Aurora Reservoir Dam,” wrote Kevin Lynch, an associate professor of law at the University of Denver Environmental Law Clinic, in an October letter to Arapahoe County commissioners on behalf of residents and conservation groups.