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Vapor Intrusion Guidance for Petroleum Sites Draws Criticism Over Proposed Changes

Thursday, December 6, 2012

State regulators and industry groups say they are concerned by the Environmental Protection Agency's attempt to craft guidance for assessing vapor intrusion at petroleum-contaminated sites that is more conservative than a version the agency previously indicated it would publish.

The concerns center on the depth of soil that is needed to cover underground storage tanks and delineation of a lateral inclusion zone, Robin Davis, an environmental scientist with the Utah Department of Environmental Quality, told BNA Dec. 4.

A lateral inclusion zone is the area surrounding a mass of underground contamination through which petroleum vapors may travel, intrude into buildings, and potentially threaten human health and the environment, according to EPA.

Soil Depth an Issue

Bruce Bauman, an environmental scientist with the American Petroleum Institute, said in a Dec. 5 email, “I think it is pretty clear” that industry was not pleased with EPA's decision to “somewhat arbitrarily increase” the clean soil screening depth from 15 feet to 30 feet.

The criticism is over draft guidance that was sent in mid-November to members of a work group convened by EPA as the agency tries to complete guidance on vapor intrusion at petroleum sites and a broader guidance document addressing vapor intrusion from other types of contamination.

EPA did not respond to the criticism when asked for comment.

EPA continues to work towards the release of final guidance for assessing and mitigating the vapor intrusion pathway, the agency said in a Dec. 4 email to BNA. Upon release, the guidance will supersede and replace EPA's 2002 Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils.

Davis was a member of an EPA advisory work group that in March approved a version of the petroleum guidance that, according to Davis, EPA suggested it intended to publish as final guidance. Later, EPA changed the document, and a version dated Oct. 18 and obtained by BNA shows the new language on the soil depth and lateral inclusion zone.

Davis called the changes “overprescriptive and overconservative” and said they “went against the recommendations of the workgroup.”

The workgroup had concluded that 15 feet of clean soil would be adequate to address vapors associated with light non-aqueous phase liquids, such as gasoline and fuel oil, Davis said.

“EPA then wanted to add another 15 feet of soil to make it 30 feet to account for uncertainties associated with” light non-aqueous phase liquids, such as gasoline and fuel oils, Davis said. A database compiled by an EPA contractor, however, already accounts for these uncertainties, she said.

Regulators and other members of the workgroup also are concerned about a chapter in the draft guidance on how to delineate the lateral inclusion zone, Davis said.

Work Group Reviewed Draft

“The chapter is complicated even for scientists and engineers,” she said. “It should be up to the regulators to determine the lateral extent--leave it to our professional judgment.”

Overly conservative guidance, she said, will result in a “waste of money” and no added health benefits at a time when state resources are very limited and some states' petroleum insurance funds are bankrupt.

Because of the concern, EPA in mid-November sent the Oct. 18 draft petroleum guidance, along with the broader guidance dated Nov. 7, to members of the workgroup for comment, Davis said.

EPA had been striving to release both sets of guidance by Nov. 30, but in October an agency official told a public meeting that he hoped it would be “months, not years” before the guidance was issued (202 DER A-17, 10/19/12).

Davis estimated that both sets of guidance would now be released in the spring of 2013.

Calls for Public Review

“Based on what I've seen of the [petroleum vapor intrusion] document, it seems to make sense for EPA to put it out for public comment beyond the limited group that now seems to be reviewing it,” Christopher Roe, an attorney with Fox Rothschild, told BNA Dec. 4.

Bauman agreed, saying, “it would have been far more productive for EPA to publish draft guidance for formal public comment.”

“Hopefully, EPA will provide sufficient documentation of the science behind their reasoning” for making the changes it did and “allow stakeholders to assess that reasoning and offer technical justifications as to why the original 15 feet guidance was correct,” he said.

In its statement to BNA, EPA said it has made “substantial progress during the past year in preparing the final guidance for the vapor intrusion pathway, including considering and addressing extensive and substantive public comments received in 2011 and 2012.”

 By Pat Ware  


The petroleum vapor intrusion draft guidance is http://op.bna.com/env.nsf/r?Open=jsun-92pu9t.

The broader vapor intrusion draft guidance is available at http://op.bna.com/env.nsf/r?Open=jsun-92pu8s.