The State Department of Environmental Protection held hearings this week on an appeal of its permitting for a proposed natural gas compressor station in Weymouth. The hearings were scheduled to wrap up today, but a twist has changed all that. Reporter Craig LeMoult has been at the hearings this week and spoke with WGBH Radio’s Judie Yuill. This transcript has been edited for clarity.

Judie Yuill: First of all, what is a compressor station and where do they want to put it in Weymouth?

Craig LeMoult: So compressor stations increase the pressure of natural gas in pipelines, speeding up the movement of the gas so it can travel further. Enbridge, which is the company that plans to build this station, says this project would provide extra capacity and move the natural gas north to be sold in Canada. I've actually been to the site where this station is proposed. It's a four acre lot in an industrial area. It's just over the huge new Fore River Bridge from Quincy. There's a sewer pumping station right there, a factory, a gas power plant, and there's also a lot of homes not far away, including an apartment complex just across the river.

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Yuill: Now residents and environmentalists have been fighting the plan to build the compressor station here. What are their concerns?

LeMoult: Well for one thing, there's a lot of people who just don't want to see the state expanding its fossil fuel infrastructure because of the impact it has on climate change. With natural gas specifically, the biggest worry is the impact of methane leaking from the system, it's a powerful greenhouse gas. There are also some concerns from people in the area about the safety of building a plant there. But neither one of those things were really discussed at the hearing this week. This is an appeal of the air quality permit that the state issued for the project. They issued it back in January. So the hearings have really been focused on the possible toxic emissions from the compressor.

Yuill: What have the hearings been like this week?

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LeMoult: You know, there's been a lot of detailed discussion about things like buoyancy induced dispersion and top case best available control technology guidelines. But under all that jargon, the main issues here are how much emissions the plant would have, what toxins are in those emissions, and what the levels of toxins are in the air at the site already?

Phillip Landrigan, the director of Boston College Global Observatory on Pollution and Health, testified on Wednesday that in this case, the DEP [Department of Environmental Protection] has not considered the existing contamination of the community as they have in prior decisions like this. “I don't think you should allow any additional benzene into this already polluted environment," he said, "if your goal is to protect human health and not to protect some other interests.” Boston University professor Nathan Phillips, who's also one of the petitioners filing the appeal, alleged in his testimony that Enbridge has improperly influenced state models of the expected emissions. And he suggested the state's support for the project is influenced by the industry's campaign donations to Governor Charlie Baker.

Yuill: And what has Baker said about all this?

LeMoult: As a governor who was recently down in D.C. testifying about climate change resiliency, I don't think this governor likes being portrayed as a boogey man by the environmentalists in the state over this issue. He's consistently tried to distance himself and the state from this decision, saying complaints should really be directed at federal authorities who have the ultimate say. But the plan does require state approvals, including this air quality permit.

Yuill: Did witnesses for Enbridge defend the plan this week?

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LeMoult: Absolutely. A lot of that came in the form of detailed written testimony that all the witnesses filed in the hearings. They've mostly been answering arcane and sometimes aggressive questioning from the attorneys challenging the project, but the witnesses have consistently been saying any emissions from the gas compressor would fall within safe limits set by the government. A consultant for Enbridge named Peter Valberg testified, saying that benzene and formaldehyde already measured in the air around the proposed site fall within what the U.S. EPA considers acceptable cancer risk range, in his words, "meaning that these hypothetical cancer risks should not be viewed as providing evidence of unacceptable existing air quality.” And a lot of the testimony has also been about the accuracy of the models used to predict the levels of those expected emissions.

Yuill: The hearings were slated to wrap up today, but that's not happening, right? What changed?

LeMoult: Well, last night, after the second day of hearings, the DEP released 759 pages of previously unreleased air quality data that the petitioners have never had a chance to see before. The data is from a private lab that the DEP used for air samples on the site, samples taken last August. I talked to Nathan Phillips of BU today about that new data and he says it shows several other toxins were found at the site that haven't been previously reported. “This is an environmental justice community," he said. "They're already overburdened with toxics, and these data have just shown that we have carcinogens at 10 times the allowable ambient level that were unreported and were un-received until last night.” Again, that's data on pollution already at the site. Whether those are some of the same toxins the compressor station might emit and what impact that might have on this permitting is something they're just going to have to hash out when these hearings reconvene after everybody's had a chance to read all of this new material.

Yuill: Okay, thanks for joining us, Craig.

LeMoult: You're welcome.

Yuill: That is WGBH Radio's Craig LeMoult, who has been covering hearings this week on a contentious plan for a natural gas compressor station in Weymouth.