California's "fracking" debate has taken a turn for the technical.

Although there's still no resolution on the politically charged question of whether oil companies should have to disclose what chemicals they use in the technique also known as hydraulic fracturing, observers are broadening the discussion to include well construction standards and other issues that are arguably more practical than simply listing secret ingredients.

Recent comments on rules proposed for the practice reflect concerns ranging from what kind of tests should be required before and after a frack job to how much cement should be poured into wells that undergo the process.

The result is that the debate is moving closer to day-to-day oil field operations in Kern County, where any new regulations would fall hardest.

Fracking injects sand, large amounts of water and small concentrations of sometimes toxic chemicals underground at high pressure to break up rock formations and release oil and natural gas. Credited with opening access to vast petroleum reserves in other states, it has been done in western Kern County for decades without reports of groundwater contamination.

Draft regulations released in December by the state Division of Oil, Gas and Geothermal Resources propose pre-fracking well tests, monitoring before and after the procedure and rules for storing and handling hydraulic fracturing fluids. Its more controversial passages spell out measures for advance notification of frack jobs and limited disclosure of materials used in the process.

Industry representatives said they are withholding judgment on the proposed rules until DOGGR enters a rulemaking stage expected to begin no later than this summer.

Detailed criticisms

Meanwhile, environmental groups are asking the division to do more to protect groundwater from fracking.

Probably the most extreme comments have come from the Arizona-based Center for Biological Diversity. In a letter last week, it asked DOGGR to ban fracking in California altogether and instead focus on developing renewable energy.

Short of total prohibition, the group joined other groups in requesting pre- and post-fracking field tests beyond those already proposed by DOGGR. It also asked the division to become more closely involved in monitoring and verifying test results.

In late February, a coalition of 18 mostly environmental activist groups sent DOGGR a 40-page letter recommending many specific changes to the draft rules.

The coalition asked that fracking be regulated under existing federal rules on waste disposal injection projects. These rules are tougher in several respects than what DOGGR has proposed.

The division and the industry maintain that these regulations, under the U.S. Environmental Protection Agency's Underground Injection Control program, are not applicable.

Among the coalition's other recommendations: Institute seismic monitoring as part of the fracking process, prohibit the practice in residential areas and other sensitive locations, and require that oil companies turn over technical models of how their frack jobs are supposed to proceed. It also asked DOGGR to raise its well cementing standards to ensure that the high pressures associated with hydraulic fracturing do not rupture underground casing pipes and allow toxic fluids to contaminate groundwater.

How we got here

DOGGR and its parent agency, the California Department of Conservation, came up with the draft rules under pressure from state lawmakers and environmentalists who accused them of ignoring a risky practice. California currently has no rules specific to fracking, and oil companies do not have to provide information about the practice.

Before releasing the draft, the division consulted a number of industry sources and environmentalists; DOGGR staff also reviewed public comments voiced during a series of seven listening sessions across the state last summer. It has emphasized that the draft regulations were intended to stimulate conversation about how the state should regulate fracking.